‘Commonsensism' refers to one of the principal approaches to traditional theory of knowledge where one asks
oneself the following Socratic questions: (1) What can I know?; (2) How can I distinguish beliefs that are
reasonable for me to have from beliefs that are not reasonable for me to have? and (3) What can I do to replace
unreasonable beliefs by reasonable beliefs about the same subject-matter, and to replace beliefs that are less
reasonable by beliefs that are more reasonable? The mark of commonsensism is essentially a faith in oneself - a
conviction that a human being, by proceeding cautiously, is capable of knowing the world in which it finds itself.
Any inquiry must set out with some beliefs. If you had no beliefs at all, you could not even begin to inquire. Hence
any set of beliefs is better than none. Moreover, the beliefs that we do find ourselves with at any given time have so
far survived previous inquiry and experience. And it is psychologically impossible to reject everything that you
believe. ‘Doubting', Peirce says, ‘is not as easy as lying'. Inquiry, guided by common sense, leads us to a set of
beliefs which indicates that common sense is on the whole a reliable guide to knowledge. And if inquiry were not
thus guided by common sense, how would it be able to answer the three Socratic questions with which it begins?
1 Background: Reid and Peirce
The term ‘commonsensism' was introduced by Charles Sanders Peirce who was concerned to contrast his own
‘critical commonsensism' with the views of Thomas Reid and with those of the other members of the Scottish
Common Sense school of philosophy. According to Reid, the ‘principles of common sense' are intuitive truths that
all sane people accept when they are not doing philosophy. They are no less reasonable than the truths of logic and
mathematics.
Reid is most persuasive in criticizing those philosophers who reject the principles of common sense. He calls our
attention to the extremes of British empiricism, culminating in the absurdities of Hume's empirical system. These
alleged absurdities include the following: we cannot know anything about the past; we cannot know whether there
are any material things; and we cannot even know that we ourselves exist. Reid observes:
A traveller of good judgment may mistake his way, but when it ends in a coal-pit, it requires no great judgment
to know that he hath gone wrong, nor perhaps to find out what misled him'. The committed empiricist who is
not yet prepared to abandon his extreme epistemological views may point out that Reid cannot demonstrate, to
the empiricist's satisfaction, that the empiricist is not in a delirium. ‘But how does he know that he is not in a
delirium? I cannot tell; neither can I tell how a man knows that he exists. But, if any man seriously doubts
whether he is in a delirium, I think it is highly probable that he is, and that it is time to seek for a cure.
A somewhat more patient and difficult response may be found in the critical commonsensism of Peirce, which may
be thought of as a refinement upon the views of Reid. Peirce says that his own view ‘arises out of a contrite
fallibilism, combined with a high faith in the reality of knowledge, and an intense desire to find things out' (Peirce) .
2 Critical commonsensism: a systematic treatment
‘The slogans are impressive enough,' one may say, ‘but how are they to be applied?' In setting out, one
presupposes that, by contemplating various possible beliefs, we can find out that some of them logically imply
others, that some contradict others, that some are such that they serve to confirm others (they make the others
probable) and that some are such as to disconfirm others (they make the others improbable). Probability, as Peirce
conceives it, is ‘a thing to be inferred upon evidence'.
Two quite different procedures are involved. The first is that of ridding ourselves of beliefs that we should not
have. The second is that of reconstruction - that of ‘building anew'. We may call the second procedure ‘the road
back'. Descartes distinguishes the two steps in the first of his Meditations: ‘I was convinced that I must once for
all seriously undertake to rid myself of all the opinions which I had formerly accepted, and commence to build
anew from the foundation'. Critical commonsensism, therefore, is a version of foundationalism.
To see how commonsensism is applied in the theory of knowledge, we should consider the ‘building anew' that is
involved in the road back. Having some faith in ourselves, we start out with our native common sense - with what
we find ourselves inclined to believe. Where else, after all, could we start out? If, like Peirce, we accept critical
commonsensism, we will make this assumption: the mere fact that we find ourselves believing one thing rather
than another is itself a prima facie reason for believing that thing. One way to improve upon this mass of uncritical
beliefs is to sift it down and try to cast away the things that should not be there. If we find a set of beliefs that
contradict each other, we will try to sift it down in such a way that the remaining set is not contradictory. If we
then find that the remaining set disconfirms some of its members, then we will proceed in analogous fashion, in the
hope that the surviving set will not thus disconfirm any of its members.
We also appeal to the experiences of perceiving and remembering. Suppose you think that you are perceiving a
sheep. That you think you are perceiving a sheep gives some prima facie justification for that belief. And at this
stage of the road back, there may be still more to be said for the belief. If the belief is confirmed by the set of other
beliefs that has so far survived your critical scrutiny, then it is more reasonable than any belief not so confirmed.
What has been said about perceiving may also be said, mutatis mutandis, about remembering. Traditional
empiricism, Peirce points out, is not adequate to the epistemic status of memory (see Empiricism). Still another
source of epistemic respectability is the possibility of concurrence (also called ‘coherence' and ‘mutual support').
A set of beliefs may be said to concur, or to be related by mutual support, provided that any of its members is
confirmed by the conjunction of all the others. If we find such a set among the beliefs that we still have, then we
may say that the whole now has a still greater degree of epistemic respectability.
In summarizing his approach to the theory of knowledge, Peirce calls attention to ‘one of the most wonderful
features of reasoning and one of the most important philosophemes in the doctrine of science, of which, however,
you will search in vain in any book I can think of: namely, that reasoning tends to correct itself, and the more so,
the more wisely its plan is laid. Nay, it not only corrects its conclusions, it even corrects its premises' (Peirce).
3 Commonsensism and metaphysics
The ‘defence of common sense' associated with G.E. Moore should not be considered as being primarily an
attempt to deal with the problems of the traditional theory of knowledge. It is intended, rather, as a corrective to
what Moore felt were some of the excesses of the metaphysicians of his day, particularly those in the tradition of
absolute idealism (see Moore, G.E. §§2-3). Some of these philosophers, for example, tried to prove that there is no
valid distinction between appearance and reality. In lectures on this topic, Moore would refute such views in the
following way. He would hold up his hand, saying ‘Here is a hand', and he would then point out that this obvious
fact was inconsistent with the proposed theory about appearance and reality. If their reasoning were sound, then
they would not be justified ‘in believing that this is a hand'. Some of these philosophers had also felt that they
could prove that ‘time is unreal'. Moore calls to their attention what, apparently, many of them had not noticed -
that their thesis has the absurd consequence that no one ever knows whether or not they had their breakfast before
having their lunch. Such refutations met with considerable indignation but not with any very convincing
rejoinders.
